feat(ui): add and remove destinations

internal/app/app.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"slices"
 	"time"
 
 	"git.netflux.io/rob/octoplex/internal/config"
@@ -17,7 +18,7 @@ import (
 
 // RunParams holds the parameters for running the application.
 type RunParams struct {
-	Config             config.Config
+	ConfigService      *config.Service
 	DockerClient       container.DockerClient
 	Screen             *terminal.Screen // Screen may be nil.
 	ClipboardAvailable bool
@@ -28,9 +29,15 @@ type RunParams struct {
 
 // Run starts the application, and blocks until it exits.
 func Run(ctx context.Context, params RunParams) error {
-	state := newStateFromRunParams(params)
+	// cfg is the current configuration of the application, as reflected in the
-	logger := params.Logger
+	// config file.
+	cfg := params.ConfigService.Current()
 
+	// state is the current state of the application, as reflected in the UI.
+	state := new(domain.AppState)
+	applyConfig(cfg, state)
+
+	logger := params.Logger
 	ui, err := terminal.StartUI(ctx, terminal.StartParams{
 		Screen:             params.Screen,
 		ClipboardAvailable: params.ClipboardAvailable,
@@ -52,7 +59,6 @@ func Run(ctx context.Context, params RunParams) error {
 	updateUI := func() { ui.SetState(*state) }
 	updateUI()
 
-	// TODO: check for unused networks.
 	var exists bool
 	if exists, err = containerClient.ContainerRunning(ctx, container.AllContainers()); err != nil {
 		return fmt.Errorf("check existing containers: %w", err)
@@ -71,12 +77,12 @@ func Run(ctx context.Context, params RunParams) error {
 	ui.AllowQuit()
 
 	// While RTMP is the only source, it doesn't make sense to disable it.
-	if !params.Config.Sources.RTMP.Enabled {
+	if !cfg.Sources.RTMP.Enabled {
 		return errors.New("config: sources.rtmp.enabled must be set to true")
 	}
 
 	srv, err := mediaserver.StartActor(ctx, mediaserver.StartActorParams{
-		StreamKey:       mediaserver.StreamKey(params.Config.Sources.RTMP.StreamKey),
+		StreamKey:       mediaserver.StreamKey(cfg.Sources.RTMP.StreamKey),
 		ContainerClient: containerClient,
 		Logger:          logger.With("component", "mediaserver"),
 	})
@@ -98,6 +104,9 @@ func Run(ctx context.Context, params RunParams) error {
 
 	for {
 		select {
+		case cfg = <-params.ConfigService.C():
+			applyConfig(cfg, state)
+			updateUI()
 		case cmd, ok := <-ui.C():
 			if !ok {
 				// TODO: keep UI open until all containers have closed
@@ -107,6 +116,24 @@ func Run(ctx context.Context, params RunParams) error {
 
 			logger.Debug("Command received", "cmd", cmd.Name())
 			switch c := cmd.(type) {
+			case terminal.CommandAddDestination:
+				cfg.Destinations = append(cfg.Destinations, config.Destination{
+					Name: c.DestinationName,
+					URL:  c.URL,
+				})
+				if err := params.ConfigService.SetConfig(cfg); err != nil {
+					// TODO: error handling
+					logger.Error("Failed to set config", "err", err)
+				}
+			case terminal.CommandRemoveDestination:
+				mp.StopDestination(c.URL) // no-op if not live
+				cfg.Destinations = slices.DeleteFunc(cfg.Destinations, func(dest config.Destination) bool {
+					return dest.URL == c.URL
+				})
+				if err := params.ConfigService.SetConfig(cfg); err != nil {
+					// TODO: error handling
+					logger.Error("Failed to set config", "err", err)
+				}
 			case terminal.CommandStartDestination:
 				mp.StartDestination(c.URL)
 			case terminal.CommandStopDestination:
@@ -183,17 +210,31 @@ func handleDestError(destError destinationError, mp *multiplexer.Actor, ui *term
 	mp.StopDestination(destError.url)
 }
 
-// newStateFromRunParams creates a new app state from the run parameters.
+// applyConfig applies the config to the app state. For now we only set the
-func newStateFromRunParams(params RunParams) *domain.AppState {
+// destinations.
-	var state domain.AppState
+func applyConfig(cfg config.Config, appState *domain.AppState) {
+	appState.Destinations = resolveDestinations(appState.Destinations, cfg.Destinations)
+}
 
-	state.Destinations = make([]domain.Destination, 0, len(params.Config.Destinations))
+// resolveDestinations merges the current destinations with newly configured
-	for _, dest := range params.Config.Destinations {
+// destinations.
-		state.Destinations = append(state.Destinations, domain.Destination{
+func resolveDestinations(destinations []domain.Destination, inDestinations []config.Destination) []domain.Destination {
-			Name: dest.Name,
+	destinations = slices.DeleteFunc(destinations, func(dest domain.Destination) bool {
-			URL:  dest.URL,
+		return !slices.ContainsFunc(inDestinations, func(inDest config.Destination) bool {
+			return inDest.URL == dest.URL
+		})
+	})
+
+	for i, inDest := range inDestinations {
+		if i < len(destinations) && destinations[i].URL == inDest.URL {
+			continue
+		}
+
+		destinations = slices.Insert(destinations, i, domain.Destination{
+			Name: inDest.Name,
+			URL:  inDest.URL,
 		})
 	}
 
-	return &state
+	return destinations[:len(inDestinations)]
 }

internal/app/app_test.go

@@ -0,0 +1,71 @@
+package app
+
+import (
+	"testing"
+
+	"git.netflux.io/rob/octoplex/internal/config"
+	"git.netflux.io/rob/octoplex/internal/domain"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestResolveDestinations(t *testing.T) {
+	testCases := []struct {
+		name     string
+		in       []config.Destination
+		existing []domain.Destination
+		want     []domain.Destination
+	}{
+		{
+			name:     "nil slices",
+			existing: nil,
+			want:     nil,
+		},
+		{
+			name:     "empty slices",
+			existing: []domain.Destination{},
+			want:     []domain.Destination{},
+		},
+		{
+			name:     "identical slices",
+			in:       []config.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.facebook.com/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}},
+			existing: []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.facebook.com/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}},
+			want:     []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.facebook.com/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}},
+		},
+		{
+			name:     "adding a new destination",
+			in:       []config.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}},
+			existing: []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}},
+			want:     []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}},
+		},
+		{
+			name:     "removing a destination",
+			in:       []config.Destination{{URL: "rtmp://rtmp.twitch.tv/live"}},
+			existing: []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}},
+			want:     []domain.Destination{{URL: "rtmp://rtmp.twitch.tv/live"}},
+		},
+		{
+			name:     "switching order, two items",
+			in:       []config.Destination{{URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.youtube.com/live"}},
+			existing: []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}},
+			want:     []domain.Destination{{URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.youtube.com/live"}},
+		},
+		{
+			name:     "switching order, several items",
+			in:       []config.Destination{{URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.facebook.com/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}},
+			existing: []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}, {URL: "rtmp://rtmp.facebook.com/live"}},
+			want:     []domain.Destination{{URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.facebook.com/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}},
+		},
+		{
+			name:     "removing all destinations",
+			in:       []config.Destination{},
+			existing: []domain.Destination{{URL: "rtmp://rtmp.youtube.com/live"}, {URL: "rtmp://rtmp.twitch.tv/live"}, {URL: "rtmp://rtmp.facebook.com/live"}, {URL: "rtmp://rtmp.tiktok.com/live"}},
+			want:     []domain.Destination{},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, resolveDestinations(tc.existing, tc.in))
+		})
+	}
+}

internal/app/integration_test.go

@@ -5,6 +5,8 @@ package app_test
 import (
 	"context"
 	"fmt"
+	"log/slog"
+	"os"
 	"runtime"
 	"sync"
 	"testing"
@@ -24,9 +26,12 @@ import (
 )
 
 func TestIntegration(t *testing.T) {
-	ctx, cancel := context.WithTimeout(t.Context(), 2*time.Minute)
+	ctx, cancel := context.WithTimeout(t.Context(), 10*time.Minute)
 	defer cancel()
 
+	configService, err := config.NewDefaultService()
+	require.NoError(t, err)
+
 	destServer, err := testcontainers.GenericContainer(ctx, testcontainers.GenericContainerRequest{
 		ContainerRequest: testcontainers.ContainerRequest{
 			Image:        "bluenviron/mediamtx:latest",
@@ -42,6 +47,7 @@ func TestIntegration(t *testing.T) {
 	require.NoError(t, err)
 
 	logger := testhelpers.NewTestLogger().With("component", "integration")
+	logger.Info("Initialised logger", "debug_level", logger.Enabled(ctx, slog.LevelDebug), "runner_debug", os.Getenv("RUNNER_DEBUG"))
 	dockerClient, err := dockerclient.NewClientWithOpts(dockerclient.FromEnv)
 	require.NoError(t, err)
 
@@ -78,6 +84,12 @@ func TestIntegration(t *testing.T) {
 		return lines
 	}
 
+	t.Cleanup(func() {
+		if t.Failed() {
+			printScreen(getContents, "After failing")
+		}
+	})
+
 	screen := tcell.NewSimulationScreen("")
 	screenCaptureC := make(chan terminal.ScreenCapture, 1)
 	go func() {
@@ -94,33 +106,31 @@ func TestIntegration(t *testing.T) {
 		}
 	}()
 
-	done := make(chan struct{})
-	go func() {
 	// https://stackoverflow.com/a/60740997/62871
 	if runtime.GOOS != "linux" {
 		panic("TODO: try host.docker.internal or Mac equivalent here")
 	}
 	const destHost = "172.17.0.1"
 
+	destURL1 := fmt.Sprintf("rtmp://%s:%d/live/dest1", destHost, destServerPort.Int())
+	destURL2 := fmt.Sprintf("rtmp://%s:%d/live/dest2", destHost, destServerPort.Int())
+	cfg := config.Config{
+		Sources: config.Sources{RTMP: config.RTMPSource{Enabled: true, StreamKey: "live"}},
+		// Load one destination from config, add the other in-app.
+		Destinations: []config.Destination{{Name: "Local server 1", URL: destURL1}},
+	}
+
+	tmpDir, err := os.MkdirTemp("", "octoplex-app-test-integration")
+	require.NoError(t, err)
+	t.Cleanup(func() { os.RemoveAll(tmpDir) })
+	configService, err = config.NewService(func() (string, error) { return tmpDir, nil }, 1)
+	require.NoError(t, err)
+	require.NoError(t, configService.SetConfig(cfg))
+
+	done := make(chan struct{})
+	go func() {
 		err := app.Run(ctx, app.RunParams{
-			Config: config.Config{
+			ConfigService: configService,
-				Sources: config.Sources{
-					RTMP: config.RTMPSource{
-						Enabled:   true,
-						StreamKey: "live",
-					},
-				},
-				Destinations: []config.Destination{
-					{
-						Name: "Local server 1",
-						URL:  fmt.Sprintf("rtmp://%s:%d/live/dest1", destHost, destServerPort.Int()),
-					},
-					{
-						Name: "Local server 2",
-						URL:  fmt.Sprintf("rtmp://%s:%d/live/dest2", destHost, destServerPort.Int()),
-					},
-				},
-			},
 			DockerClient:  dockerClient,
 			Screen: &terminal.Screen{
 				Screen:   screen,
@@ -137,17 +147,79 @@ func TestIntegration(t *testing.T) {
 		done <- struct{}{}
 	}()
 
-	// Wait for mediaserver container to start:
 	time.Sleep(5 * time.Second)
+	require.EventuallyWithT(
+		t,
+		func(t *assert.CollectT) {
+			contents := getContents()
+			require.True(t, len(contents) > 2, "expected at least 3 lines of output")
+
+			assert.Contains(t, contents[2], "Status   ready", "expected mediaserver status to be ready")
+		},
+		2*time.Minute,
+		time.Second,
+		"expected the mediaserver to start",
+	)
+	printScreen(getContents, "After starting the mediaserver")
 
 	// Start streaming a test video to the app:
 	testhelpers.StreamFLV(t, "rtmp://localhost:1935/live")
-	time.Sleep(10 * time.Second)
+
+	require.EventuallyWithT(
+		t,
+		func(t *assert.CollectT) {
+			contents := getContents()
+			require.True(t, len(contents) > 2, "expected at least 3 lines of output")
+
+			assert.Contains(t, contents[2], "Status   receiving", "expected mediaserver status to be receiving")
+			assert.Contains(t, contents[3], "Tracks   H264", "expected mediaserver tracks to be H264")
+			assert.Contains(t, contents[4], "Health   healthy", "expected mediaserver to be healthy")
+		},
+		time.Minute,
+		time.Second,
+		"expected to receive an ingress stream",
+	)
+	printScreen(getContents, "After receiving the ingress stream")
+
+	// Add a second destination in-app:
+	sendKey(screen, tcell.KeyRune, 'a')
+
+	sendBackspaces(screen, 30)
+	sendKeys(screen, "Local server 2")
+	sendKey(screen, tcell.KeyTab, ' ')
+
+	sendBackspaces(screen, 30)
+	sendKeys(screen, destURL2)
+	sendKey(screen, tcell.KeyTab, ' ')
+	sendKey(screen, tcell.KeyEnter, ' ')
+
+	require.EventuallyWithT(
+		t,
+		func(t *assert.CollectT) {
+			contents := getContents()
+			require.True(t, len(contents) > 2, "expected at least 3 lines of output")
+
+			assert.Contains(t, contents[2], "Status   receiving", "expected mediaserver status to be receiving")
+			assert.Contains(t, contents[3], "Tracks   H264", "expected mediaserver tracks to be H264")
+			assert.Contains(t, contents[4], "Health   healthy", "expected mediaserver to be healthy")
+
+			require.Contains(t, contents[2], "Local server 1", "expected local server 1 to be present")
+			assert.Contains(t, contents[2], "off-air", "expected local server 1 to be off-air")
+
+			require.Contains(t, contents[3], "Local server 2", "expected local server 2 to be present")
+			assert.Contains(t, contents[3], "off-air", "expected local server 2 to be off-air")
+
+		},
+		2*time.Minute,
+		time.Second,
+		"expected to add the destinations",
+	)
+	printScreen(getContents, "After adding the destinations")
 
 	// Start destinations:
-	screen.PostEvent(tcell.NewEventKey(tcell.KeyRune, ' ', tcell.ModNone))
+	sendKey(screen, tcell.KeyRune, ' ')
-	screen.PostEvent(tcell.NewEventKey(tcell.KeyDown, ' ', tcell.ModNone))
+	sendKey(screen, tcell.KeyDown, ' ')
-	screen.PostEvent(tcell.NewEventKey(tcell.KeyRune, ' ', tcell.ModNone))
+	sendKey(screen, tcell.KeyRune, ' ')
 
 	require.EventuallyWithT(
 		t,
@@ -166,18 +238,43 @@ func TestIntegration(t *testing.T) {
 			require.Contains(t, contents[3], "Local server 2", "expected local server 2 to be present")
 			assert.Contains(t, contents[3], "sending", "expected local server 2 to be sending")
 			assert.Contains(t, contents[3], "healthy", "expected local server 2 to be healthy")
+		},
+		2*time.Minute,
+		time.Second,
+		"expected to start the destination streams",
+	)
+	printScreen(getContents, "After starting the destination streams")
+
+	sendKey(screen, tcell.KeyRune, 'r')
+	sendKey(screen, tcell.KeyEnter, ' ')
+
+	require.EventuallyWithT(
+		t,
+		func(t *assert.CollectT) {
+			contents := getContents()
+			require.True(t, len(contents) > 2, "expected at least 3 lines of output")
+
+			assert.Contains(t, contents[2], "Status   receiving", "expected mediaserver status to be receiving")
+			assert.Contains(t, contents[3], "Tracks   H264", "expected mediaserver tracks to be H264")
+			assert.Contains(t, contents[4], "Health   healthy", "expected mediaserver to be healthy")
+
+			require.Contains(t, contents[2], "Local server 1", "expected local server 1 to be present")
+			assert.Contains(t, contents[2], "sending", "expected local server 1 to be sending")
+			assert.Contains(t, contents[2], "healthy", "expected local server 1 to be healthy")
+
+			require.NotContains(t, contents[3], "Local server 2", "expected local server 2 to not be present")
 
 		},
 		2*time.Minute,
 		time.Second,
+		"expected to remove the second destination",
 	)
+	printScreen(getContents, "After removing the second destination")
 
-	// Stop destinations:
+	// Stop remaining destination.
-	screen.PostEvent(tcell.NewEventKey(tcell.KeyRune, ' ', tcell.ModNone))
+	// It is currently necessary to press down to re-focus the destination:
-	screen.PostEvent(tcell.NewEventKey(tcell.KeyUp, ' ', tcell.ModNone))
+	sendKey(screen, tcell.KeyDown, ' ')
-	screen.PostEvent(tcell.NewEventKey(tcell.KeyRune, ' ', tcell.ModNone))
+	sendKey(screen, tcell.KeyRune, ' ')
-
-	time.Sleep(10 * time.Second)
 
 	require.EventuallyWithT(
 		t,
@@ -188,13 +285,15 @@ func TestIntegration(t *testing.T) {
 			require.Contains(t, contents[2], "Local server 1", "expected local server 1 to be present")
 			assert.Contains(t, contents[2], "exited", "expected local server 1 to have exited")
 
-			require.Contains(t, contents[3], "Local server 2", "expected local server 2 to be present")
+			require.NotContains(t, contents[3], "Local server 2", "expected local server 2 to not be present")
-			assert.Contains(t, contents[3], "exited", "expected local server 2 to have exited")
 		},
-		2*time.Minute,
+		time.Minute,
 		time.Second,
+		"expected to stop the first destination stream",
 	)
 
+	printScreen(getContents, "After stopping the first destination")
+
 	// TODO:
 	// - Source error
 	// - Destination error
@@ -204,3 +303,27 @@ func TestIntegration(t *testing.T) {
 
 	<-done
 }
+
+func printScreen(getContents func() []string, label string) {
+	fmt.Println(label + ":")
+	for _, line := range getContents() {
+		fmt.Println(line)
+	}
+}
+
+func sendKey(screen tcell.SimulationScreen, key tcell.Key, ch rune) {
+	screen.InjectKey(key, ch, tcell.ModNone)
+	time.Sleep(50 * time.Millisecond)
+}
+func sendKeys(screen tcell.SimulationScreen, keys string) {
+	screen.InjectKeyBytes([]byte(keys))
+	time.Sleep(500 * time.Millisecond)
+}
+
+func sendBackspaces(screen tcell.SimulationScreen, n int) {
+	for range n {
+		screen.InjectKey(tcell.KeyBackspace, ' ', tcell.ModNone)
+		time.Sleep(50 * time.Millisecond)
+	}
+	time.Sleep(500 * time.Millisecond)
+}

internal/config/service.go

@@ -17,25 +17,29 @@ var exampleConfig []byte
 
 // Service provides configuration services.
 type Service struct {
-	userConfigDir string
+	current      Config
 	appConfigDir string
 	appStateDir  string
+	configC      chan Config
 }
 
 // ConfigDirFunc is a function that returns the user configuration directory.
 type ConfigDirFunc func() (string, error)
 
+// defaultChanSize is the default size of the configuration channel.
+const defaultChanSize = 64
+
 // NewDefaultService creates a new service with the default configuration file
 // location.
 func NewDefaultService() (*Service, error) {
-	return NewService(os.UserConfigDir)
+	return NewService(os.UserConfigDir, defaultChanSize)
 }
 
 // NewService creates a new service with provided ConfigDirFunc.
 //
 // The app data directories (config and state) are created if they do not
 // exist.
-func NewService(configDirFunc ConfigDirFunc) (*Service, error) {
+func NewService(configDirFunc ConfigDirFunc, chanSize int) (*Service, error) {
 	configDir, err := configDirFunc()
 	if err != nil {
 		return nil, fmt.Errorf("user config dir: %w", err)
@@ -51,18 +55,37 @@ func NewService(configDirFunc ConfigDirFunc) (*Service, error) {
 		return nil, fmt.Errorf("app state dir: %w", err)
 	}
 
-	return &Service{
+	svc := &Service{
-		userConfigDir: configDir,
 		appConfigDir: appConfigDir,
 		appStateDir:  appStateDir,
-	}, nil
+		configC:      make(chan Config, chanSize),
 	}
 
-// ReadOrCreateConfig reads the configuration from the file at the given path or
+	svc.setDefaults(&svc.current)
-// creates it with default values.
+
+	return svc, nil
+}
+
+// Current returns the current configuration.
+//
+// This will be the last-loaded or last-updated configuration, or a default
+// configuration if nothing else is available.
+func (s *Service) Current() Config {
+	return s.current
+}
+
+// C returns a channel that receives configuration updates.
+//
+// The channel is never closed.
+func (s *Service) C() <-chan Config {
+	return s.configC
+}
+
+// ReadOrCreateConfig reads the configuration from the file or creates it with
+// default values.
 func (s *Service) ReadOrCreateConfig() (cfg Config, _ error) {
 	if _, err := os.Stat(s.Path()); os.IsNotExist(err) {
-		return s.createConfig()
+		return s.writeDefaultConfig()
 	} else if err != nil {
 		return cfg, fmt.Errorf("stat: %w", err)
 	}
@@ -70,6 +93,29 @@ func (s *Service) ReadOrCreateConfig() (cfg Config, _ error) {
 	return s.readConfig()
 }
 
+// SetConfig sets the configuration to the given value and writes it to the
+// file.
+func (s *Service) SetConfig(cfg Config) error {
+	cfgBytes, err := yaml.Marshal(cfg)
+	if err != nil {
+		return fmt.Errorf("marshal: %w", err)
+	}
+
+	if err = s.writeConfig(cfgBytes); err != nil {
+		return fmt.Errorf("write config: %w", err)
+	}
+
+	s.current = cfg
+	s.configC <- cfg
+
+	return nil
+}
+
+// Path returns the path to the configuration file.
+func (s *Service) Path() string {
+	return filepath.Join(s.appConfigDir, "config.yaml")
+}
+
 func (s *Service) readConfig() (cfg Config, _ error) {
 	contents, err := os.ReadFile(s.Path())
 	if err != nil {
@@ -86,23 +132,34 @@ func (s *Service) readConfig() (cfg Config, _ error) {
 		return cfg, err
 	}
 
+	s.current = cfg
+
+	return s.current, nil
+}
+
+func (s *Service) writeDefaultConfig() (Config, error) {
+	var cfg Config
+	if err := yaml.Unmarshal(exampleConfig, &cfg); err != nil {
+		return cfg, fmt.Errorf("unmarshal: %w", err)
+	}
+
+	if err := s.writeConfig(exampleConfig); err != nil {
+		return Config{}, fmt.Errorf("write config: %w", err)
+	}
+
 	return cfg, nil
 }
 
-func (s *Service) createConfig() (Config, error) {
+func (s *Service) writeConfig(cfgBytes []byte) error {
 	if err := os.MkdirAll(s.appConfigDir, 0744); err != nil {
-		return Config{}, fmt.Errorf("mkdir: %w", err)
+		return fmt.Errorf("mkdir: %w", err)
 	}
 
-	if err := os.WriteFile(s.Path(), exampleConfig, 0644); err != nil {
+	if err := os.WriteFile(s.Path(), cfgBytes, 0644); err != nil {
-		return Config{}, fmt.Errorf("write file: %w", err)
+		return fmt.Errorf("write file: %w", err)
 	}
 
-	return Config{}, nil
+	return nil
-}
-
-func (s *Service) Path() string {
-	return filepath.Join(s.appConfigDir, "config.yaml")
 }
 
 func (s *Service) setDefaults(cfg *Config) {
@@ -110,6 +167,8 @@ func (s *Service) setDefaults(cfg *Config) {
 		cfg.LogFile.Path = filepath.Join(s.appStateDir, domain.AppName+".log")
 	}
 
+	cfg.Sources.RTMP.Enabled = true
+
 	for i := range cfg.Destinations {
 		if strings.TrimSpace(cfg.Destinations[i].Name) == "" {
 			cfg.Destinations[i].Name = fmt.Sprintf("Stream %d", i+1)

internal/config/service_test.go

@@ -31,14 +31,26 @@ var configInvalidDestinationURL []byte
 //go:embed testdata/multiple-invalid-destination-urls.yml
 var configMultipleInvalidDestinationURLs []byte
 
+func TestConfigServiceCurrent(t *testing.T) {
+	suffix := "current_" + shortid.New().String()
+	systemConfigDirFunc := buildSystemConfigDirFunc(suffix)
+	systemConfigDir, _ := systemConfigDirFunc()
+
+	service, err := config.NewService(systemConfigDirFunc, 1)
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, os.RemoveAll(systemConfigDir)) })
+
+	// Ensure defaults are set:
+	assert.True(t, service.Current().Sources.RTMP.Enabled)
+}
+
 func TestConfigServiceCreateConfig(t *testing.T) {
 	suffix := "read_or_create_" + shortid.New().String()
 	systemConfigDirFunc := buildSystemConfigDirFunc(suffix)
 	systemConfigDir, _ := systemConfigDirFunc()
 
-	service, err := config.NewService(systemConfigDirFunc)
+	service, err := config.NewService(systemConfigDirFunc, 1)
 	require.NoError(t, err)
-
 	t.Cleanup(func() { require.NoError(t, os.RemoveAll(systemConfigDir)) })
 
 	cfg, err := service.ReadOrCreateConfig()
@@ -131,7 +143,7 @@ func TestConfigServiceReadConfig(t *testing.T) {
 			configPath := filepath.Join(appConfigDir, "config.yaml")
 			require.NoError(t, os.WriteFile(configPath, tc.configBytes, 0644))
 
-			service, err := config.NewService(buildSystemConfigDirFunc(suffix))
+			service, err := config.NewService(buildSystemConfigDirFunc(suffix), 1)
 			require.NoError(t, err)
 
 			cfg, err := service.ReadOrCreateConfig()
@@ -146,6 +158,25 @@ func TestConfigServiceReadConfig(t *testing.T) {
 	}
 }
 
+func TestConfigServiceSetConfig(t *testing.T) {
+	suffix := "set_config_" + shortid.New().String()
+	systemConfigDirFunc := buildSystemConfigDirFunc(suffix)
+	systemConfigDir, _ := systemConfigDirFunc()
+
+	service, err := config.NewService(systemConfigDirFunc, 1)
+	require.NoError(t, err)
+	t.Cleanup(func() { require.NoError(t, os.RemoveAll(systemConfigDir)) })
+
+	cfg := config.Config{LogFile: config.LogFile{Enabled: true, Path: "test.log"}}
+	require.NoError(t, service.SetConfig(cfg))
+
+	cfg, err = service.ReadOrCreateConfig()
+	require.NoError(t, err)
+
+	assert.Equal(t, "test.log", cfg.LogFile.Path)
+	assert.True(t, cfg.LogFile.Enabled)
+}
+
 // buildAppConfigDir returns a temporary directory which mimics
 // $XDG_CONFIG_HOME/octoplex.
 func buildAppConfigDir(suffix string) string {

internal/config/xdg.go

@@ -28,7 +28,7 @@ func createAppStateDir() (string, error) {
 	var dir string
 	switch runtime.GOOS {
 	case "darwin":
-		dir = filepath.Join(userHomeDir, "/Library", "Caches", domain.AppName)
+		dir = filepath.Join(userHomeDir, "Library", "Caches", domain.AppName)
 	case "windows":
 		// TODO: Windows support
 		return "", errors.New("not implemented")

internal/terminal/command.go

@@ -1,5 +1,26 @@
 package terminal
 
+// CommandAddDestination adds a destination.
+type CommandAddDestination struct {
+	DestinationName string
+	URL             string
+}
+
+// Name implements the Command interface.
+func (c CommandAddDestination) Name() string {
+	return "add_destination"
+}
+
+// CommandRemoveDestination removes a destination.
+type CommandRemoveDestination struct {
+	URL string
+}
+
+// Name implements the Command interface.
+func (c CommandRemoveDestination) Name() string {
+	return "remove_destination"
+}
+
 // CommandStartDestination starts a destination.
 type CommandStartDestination struct {
 	URL string

internal/terminal/terminal.go

@@ -163,6 +163,8 @@ func StartUI(ctx context.Context, params StartParams) (*UI, error) {
 	aboutView.SetDirection(tview.FlexRow)
 	aboutView.SetBorder(true)
 	aboutView.SetTitle("Actions")
+	aboutView.AddItem(tview.NewTextView().SetText("[a] Add new destination"), 1, 0, false)
+	aboutView.AddItem(tview.NewTextView().SetText("[r] Remove destination"), 1, 0, false)
 	aboutView.AddItem(tview.NewTextView().SetText("[Space] Toggle destination"), 1, 0, false)
 	aboutView.AddItem(tview.NewTextView().SetText("[u] Copy ingress RTMP URL"), 1, 0, false)
 	aboutView.AddItem(tview.NewTextView().SetText("[c] Copy config file path"), 1, 0, false)
@@ -189,7 +191,7 @@ func StartUI(ctx context.Context, params StartParams) (*UI, error) {
 		AddItem(destView, 0, 6, false)
 
 	pages := tview.NewPages()
-	pages.AddPage("main", flex, true, true)
+	pages.AddPage(pageNameMain, flex, true, true)
 
 	app.SetRoot(pages, true)
 	app.SetFocus(destView)
@@ -218,9 +220,26 @@ func StartUI(ctx context.Context, params StartParams) (*UI, error) {
 	}
 
 	app.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+		// Special case: allow all keys except Escape to be passed to the add
+		// destination modal.
+		if pageName, _ := pages.GetFrontPage(); pageName == pageNameAddDestination {
+			if event.Key() == tcell.KeyEscape {
+				ui.closeDestinationForm()
+				return nil
+			}
+
+			return event
+		}
+
 		switch event.Key() {
 		case tcell.KeyRune:
 			switch event.Rune() {
+			case 'a', 'A':
+				ui.addDestination()
+				return nil
+			case 'r', 'R':
+				ui.removeDestination()
+				return nil
 			case ' ':
 				ui.toggleDestination()
 			case 'u', 'U':
@@ -287,7 +306,7 @@ func (ui *UI) ShowStartupCheckModal() bool {
 
 	ui.app.QueueUpdateDraw(func() {
 		ui.showModal(
-			modalGroupStartupCheck,
+			pageNameModalStartupCheck,
 			"Another instance of Octoplex may already be running. Pressing continue will close that instance. Continue?",
 			[]string{"Continue", "Exit"},
 			func(buttonIndex int, _ string) {
@@ -309,7 +328,7 @@ func (ui *UI) ShowDestinationErrorModal(name string, err error) {
 
 	ui.app.QueueUpdateDraw(func() {
 		ui.showModal(
-			modalGroupStartupCheck,
+			pageNameModalStartupCheck,
 			fmt.Sprintf(
 				"Streaming to %s failed:\n\n%s",
 				cmp.Or(name, "this destination"),
@@ -395,7 +414,9 @@ func (ui *UI) updatePullProgress(state domain.AppState) {
 	}
 
 	if len(pullingContainers) == 0 {
-		ui.hideModal(modalGroupPullProgress)
+		ui.app.QueueUpdateDraw(func() {
+			ui.hideModal(pageNameModalPullProgress)
+		})
 		return
 	}
 
@@ -410,7 +431,7 @@ func (ui *UI) updatePullProgress(state domain.AppState) {
 
 func (ui *UI) updateProgressModal(container domain.Container) {
 	ui.app.QueueUpdateDraw(func() {
-		modalName := "modal-" + string(modalGroupPullProgress)
+		modalName := string(pageNameModalPullProgress)
 
 		var status string
 		// Avoid showing the long Docker pull status in the modal content.
@@ -434,21 +455,23 @@ func (ui *UI) updateProgressModal(container domain.Container) {
 	})
 }
 
-// modalGroup represents a specific modal of which only one may be shown
+// page names represent a specific page in the terminal user interface.
-// simultaneously.
+//
-type modalGroup string
+// Modals should generally have a unique name, which allows them to be stacked
-
+// on top of other modals.
 const (
-	modalGroupAbout        modalGroup = "about"
+	pageNameMain                   = "main"
-	modalGroupQuit         modalGroup = "quit"
+	pageNameAddDestination         = "add-destination"
-	modalGroupStartupCheck modalGroup = "startup-check"
+	pageNameModalAbout             = "modal-about"
-	modalGroupClipboard    modalGroup = "clipboard"
+	pageNameModalQuit              = "modal-quit"
-	modalGroupPullProgress modalGroup = "pull-progress"
+	pageNameModalStartupCheck      = "modal-startup-check"
+	pageNameModalClipboard         = "modal-clipboard"
+	pageNameModalPullProgress      = "modal-pull-progress"
+	pageNameModalRemoveDestination = "modal-remove-destination"
 )
 
-func (ui *UI) showModal(group modalGroup, text string, buttons []string, doneFunc func(int, string)) {
+func (ui *UI) showModal(pageName string, text string, buttons []string, doneFunc func(int, string)) {
-	modalName := "modal-" + string(group)
+	if ui.pages.HasPage(pageName) {
-	if ui.pages.HasPage(modalName) {
 		return
 	}
 
@@ -458,9 +481,9 @@ func (ui *UI) showModal(group modalGroup, text string, buttons []string, doneFun
 		SetBackgroundColor(tcell.ColorBlack).
 		SetTextColor(tcell.ColorWhite).
 		SetDoneFunc(func(buttonIndex int, buttonLabel string) {
-			ui.pages.RemovePage(modalName)
+			ui.pages.RemovePage(pageName)
 
-			if ui.pages.GetPageCount() == 1 {
+			if name, _ := ui.pages.GetFrontPage(); name == pageNameMain {
 				ui.app.SetFocus(ui.destView)
 			}
 
@@ -470,16 +493,15 @@ func (ui *UI) showModal(group modalGroup, text string, buttons []string, doneFun
 		}).
 		SetBorderStyle(tcell.StyleDefault.Background(tcell.ColorBlack).Foreground(tcell.ColorWhite))
 
-	ui.pages.AddPage(modalName, modal, true, true)
+	ui.pages.AddPage(pageName, modal, true, true)
 }
 
-func (ui *UI) hideModal(group modalGroup) {
+func (ui *UI) hideModal(pageName string) {
-	modalName := "modal-" + string(group)
+	if !ui.pages.HasPage(pageName) {
-	if !ui.pages.HasPage(modalName) {
 		return
 	}
 
-	ui.pages.RemovePage(modalName)
+	ui.pages.RemovePage(pageName)
 	ui.app.SetFocus(ui.destView)
 }
 
@@ -637,6 +659,83 @@ func (ui *UI) Close() {
 	ui.app.Stop()
 }
 
+func (ui *UI) addDestination() {
+	// TODO: check for existing
+	const (
+		inputLen        = 60
+		inputLabelName  = "Name"
+		inputLabelURL   = "RTMP URL"
+		formInnerWidth  = inputLen + 8 + 1 // inputLen + length of longest label + one space
+		formInnerHeight = 7                // line count from first input field to last button
+		formWidth       = formInnerWidth + 4
+		formHeight      = formInnerHeight + 2
+	)
+
+	var currWidth, currHeight int
+	if name, frontPage := ui.pages.GetFrontPage(); name == pageNameMain {
+		_, _, currWidth, currHeight = frontPage.GetRect()
+	} else {
+		return
+	}
+
+	form := tview.NewForm()
+	form.
+		AddInputField(inputLabelName, "My stream", inputLen, nil, nil).
+		AddInputField(inputLabelURL, "rtmp://", inputLen, nil, nil).
+		AddButton("Add", func() {
+			ui.commandCh <- CommandAddDestination{
+				DestinationName: form.GetFormItemByLabel(inputLabelName).(*tview.InputField).GetText(),
+				URL:             form.GetFormItemByLabel(inputLabelURL).(*tview.InputField).GetText(),
+			}
+			ui.closeDestinationForm()
+		}).
+		AddButton("Cancel", func() {
+			ui.closeDestinationForm()
+		}).
+		SetFieldBackgroundColor(tcell.ColorDarkSlateGrey).
+		SetBorder(true).
+		SetTitle("Add a new destination").
+		SetTitleAlign(tview.AlignLeft).
+		SetRect((currWidth-formWidth)/2, (currHeight-formHeight)/2, formWidth, formHeight)
+
+	ui.pages.AddPage(pageNameAddDestination, form, false, true)
+}
+
+func (ui *UI) removeDestination() {
+	const urlCol = 1
+	row, _ := ui.destView.GetSelection()
+	url, ok := ui.destView.GetCell(row, urlCol).GetReference().(string)
+	if !ok {
+		return
+	}
+
+	var started bool
+	ui.mu.Lock()
+	started = ui.urlsToStartState[url] != startStateNotStarted
+	ui.mu.Unlock()
+
+	text := "Are you sure you want to remove the destination?"
+	if started {
+		text += "\n\nThis will stop the current live stream for this destination."
+	}
+
+	ui.showModal(
+		pageNameModalRemoveDestination,
+		text,
+		[]string{"Remove", "Cancel"},
+		func(buttonIndex int, _ string) {
+			if buttonIndex == 0 {
+				ui.commandCh <- CommandRemoveDestination{URL: url}
+			}
+		},
+	)
+}
+
+func (ui *UI) closeDestinationForm() {
+	ui.pages.RemovePage(pageNameAddDestination)
+	ui.app.SetFocus(ui.destView)
+}
+
 func (ui *UI) toggleDestination() {
 	const urlCol = 1
 	row, _ := ui.destView.GetSelection()
@@ -685,7 +784,7 @@ func (ui *UI) copySourceURLToClipboard(clipboardAvailable bool) {
 	}
 
 	ui.showModal(
-		modalGroupClipboard,
+		pageNameModalClipboard,
 		text,
 		[]string{"Ok"},
 		nil,
@@ -706,7 +805,7 @@ func (ui *UI) copyConfigFilePathToClipboard(clipboardAvailable bool, configFileP
 	}
 
 	ui.showModal(
-		modalGroupClipboard,
+		pageNameModalClipboard,
 		text,
 		[]string{"Ok"},
 		nil,
@@ -724,7 +823,7 @@ func (ui *UI) confirmQuit() {
 	}
 
 	ui.showModal(
-		modalGroupQuit,
+		pageNameModalQuit,
 		"Are you sure you want to quit?",
 		[]string{"Quit", "Cancel"},
 		func(buttonIndex int, _ string) {
@@ -743,7 +842,7 @@ func (ui *UI) showAbout() {
 	}
 
 	ui.showModal(
-		modalGroupAbout,
+		pageNameModalAbout,
 		fmt.Sprintf(
 			"%s: live stream multiplexer\n(c) Rob Watson\nhttps://git.netflux.io/rob/octoplex\n\nReleased under AGPL3.\n\nv%s (%s)\nBuilt on %s (%s).",
 			domain.AppName,

main.go

@@ -89,7 +89,7 @@ func run(ctx context.Context) error {
 	return app.Run(
 		ctx,
 		app.RunParams{
-			Config:             cfg,
+			ConfigService:      configService,
 			DockerClient:       dockerClient,
 			ClipboardAvailable: clipboardAvailable,
 			ConfigFilePath:     configService.Path(),